The present invention relates to portable heating devices for cooking food on a large scale. Specifically, a heating device which is capable of heating up to 30 gallons of water or other liquids under extreme environmental conditions is described.
When responding to natural disasters, such as floods, earthquakes, etc. it is necessary to feed large numbers of people under extreme environmental conditions. These events often require that large numbers of people be fed without the usual conveniences of electric power and fuel.
The military faces similar circumstances in that exercises are conducted in the field without permanent cooking facilities. One technique of cooking utilized on a large scale by the military involves heating prepackaged tray rations of food. Tray rations contain precooked portions of food sealed in a metal or plastic container. When it is time to prepare the food for consumption, the tray rations are inserted in a bath of hot water and heated to a temperature of substantially 190.degree. F. The heating devices for heating the hot water include a reservoir having a heat exchanger immersed in the bottom of the reservoir coupled to a burner. The burner fires into the heat exchanger which in turn heats the water to the necessary temperature.
The conditions under which such tray ration heaters are used often result in significant contamination of the water reservoir. The presence of the heat exchanger in the bottom of the reservoir makes cleaning any such devices very tedious, and in some cases, ineffective depending on the nature of the contamination. The immersed heat exchanger also limits the utility of the device. For example, if the heat exchanger could be removed and hot water maintained within the device without the heat exchanger, the reservoir could be used for cleaning pots, pans, cooking utensils, etc, as well as a cooking vessel.
The tray ration heater must be portable as well as operational under mobile conditions. When a military force is on the move, meals necessarily have to be prepared while the tray ration heater is still in transit. This imposes other conditions on the design of these devices, so that there is no significant spillage or danger to the personnel preparing food using these devices. Further, the tray ration heater must also maintain an exterior temperature cool enough for personnel to touch during operation as well as to be able to move them on and off the mobile vehicle after they have cooked a set of rations without having to wait for the device to cool down.
The present invention is directed to an improved tray ration heater which maintains a sufficiently cool exterior temperature while at the same time providing a large reservoir of hot water without an internal heat exchanger.